Navigate to (https://u.muxy.io/dashboard/alertpackages) and select
an alert package to edit. You will see a window marked "Alert
Package Settings" and below that you will see a second window. In
this second window, at the top left, you will see a button that
reads "Simple". Click next to that button to get into advanced mode.
Once in the advanced mode, HTML and CSS are available from the top
right of the second window.
If you need help with your custom alerts, try asking in our Advanced Alerts Discord channel
Keywords: HTML, CSS, Advanced, mode